isatty

Synopsis:

int isatty(int fd);

Request:

‘Fisatty,fd’

Return value:

Returns 1 if fd refers to the gdb console, 0 otherwise.

Errors:

EINTR

The call was interrupted by the user.

Note that the isatty call is treated as a special case: it returns
1 to the target if the file descriptor is attached
to the gdb console, 0 otherwise. Implementing through system calls
would require implementing ioctl and would be more complex than
needed.